1. Field of the Invention
The present invention relates to a magnetic tape driving apparatus that can drive a magnetic tape. In particular, the present invention is useful for a magnetic tape apparatus that uses a magnetic sensor head to linearly record data on a magnetic tape with a surface smoothness Ra of 3.0 nm or less.
2. Description of Related Art
A magnetic tape is a kind of magnetic recording medium and for various applications such as an audio tape, a video tape, and a computer tape. Particularly, in the field of backup tapes for computers, tapes with a storage capacity of hundreds of gigabytes per volume have been commercialized along with an increase in capacity of a hard disk to be backed up. In the future, backup tapes with a larger capacity are essential to deal with a further increase in capacity of the hard disk.
For a magnetic tape used as a backup tape, the recording wavelength becomes shorter as the recording capacity increases further, and the surface smoothness has been improved to suppress the degradation of recording/reproducing characteristics due to spacing. When the surface of the magnetic tape is smoothed, the contact area between the magnetic tape and a magnetic head is increased, thus increasing friction between them. Particularly, static friction occurs, e.g., at the time the magnetic tape that is in contact with the magnetic head starts running. If this static friction is increased, the magnetic tape and the magnetic head can be damaged, or the surface of the magnetic tape can be scraped off by the magnetic head to generate foreign matter (contamination). In order to address such static friction between the magnetic head and the magnetic tape, e.g., Patent Document 1 (JP 2006-127666 A) discloses the following technology.
In Patent Document 1, small recesses are formed in a BOT (beginning of tape) portion and an EOT (end of tape) portion so as to reduce static friction between the magnetic tape and the magnetic head during magnetic recording and reproduction. With this configuration, even if the magnetic tape starts running while the magnetic head is positioned at the BOT portion or the EOT portion, tape damage can be suppressed because of reduced static friction.
However, in the configuration of Patent Document 1, the recesses are formed only in the BOT portion and EOT portion of the magnetic tape. Therefore, when the start and stop motions of the magnetic tape are repeated with the magnetic head being in contact with the portion an which no recess is formed) between the BOT and EOT portions, the magnetic head or the magnetic tape are damaged by the static friction between them.
Specifically, when the magnetic tape makes a transition from the stopped state to the running state, it sticks to the magnetic head due to the static friction between the magnetic tape and the magnetic head. Thus, the magnetic tape can be damaged or even cut. The static friction also can damage the MR element or the like of the magnetic head. Moreover, the same problem arises when the magnetic tape makes a transition from the running state to the stopped state. Further, the same problem also arises when the running direction of the magnetic tape is changed from the first (e.g., forward) direction to the second (e.g., reverse) direction and vice versa.